1. Field of the Invention
This invention relates to a new method for preparing anhydrous TaF.sub.5. More particularly, this invention relates to the preparation of anhydrous TaF.sub.5 from a mixture of water and fluorotantalic acids using one or more dehydrating agents.
2. Description of the Prior Art
TaF.sub.5 is usually produced from tantalum metal or tantalum pentachloride by reaction with a variety of fluorinating agents such as HF, F.sub.2, BrF.sub.3, SnF.sub.2 and the like (see for example F, Fairbrother, The Chemistry of Niobium and Tantalum; pages 74-88, Elsevier Publishing Co., New York 1961 and F. Fairbrother "The Halides of Niobium and Tantalum", Halogen Chemistry, Vol. 3, pages 123-131, 1967, the disclosures of which are incorporated herein by reference). However, tantalum metal is normally produced by the electrolysis of potassium fluorotantalate at temperatures of 800.degree. C. or more, or by the reaction of potassium fluorotantalate using sodium metal, or by the reaction of tantalum carbide-tantalum oxide at temperatures of about 2000.degree. C. (see Clifford A. Hampel, Rare Metals Handbook, 2nd Ed., Chapter 25, pages 472-476, Reinhold Publishing Corp., New York, 1961, the disclosure of which is incorporated herein by reference).
Similarly, tantalum pentachloride is often manufactured by chlorinating the pentoxide at elevated temperatures, e.g. temperatures of about 500.degree. C. (see F. Fairbrother, The Chemistry of Niobium and Tantalum, as above). In addition to the need for such severe conditions, the use of fluorine is expensive and requires special equipment to compensate for the corrosive nature of the gas.
Therefore, in view of the disadvantages associated with the prior art processes, it would be desirable to have a simple and inexpensive technique for preparing anhydrous tantalum pentafluoride.